RFR: 7526: JMC not buildable with jdk17 [v7]

[Christoph Langer]

On Fri, 21 Jan 2022 11:13:36 GMT, Brice Dutheil <duke at openjdk.java.net> wrote:

>> It's weird: the problem does not occur on JDK 11 with the newer p2-maven-plugin. So it might the JDK itself?
>
> Could it be a tycho issue, again. Tycho overrides many lifecycle of Maven:
> 
> https://github.com/eclipse/tycho/blob/5c83ecd968eae37aa328020d228c8f03b2a3168c/tycho-maven-plugin/src/main/resources/META-INF/plexus/components.xml#L27-L29
> 
> 
> <compile>
>   org.eclipse.tycho:tycho-compiler-plugin:${project.version}:compile
> </compile>
> 
> 
> _By the way tycho 2.6.0 seems to be [around the corner](https://github.com/eclipse/tycho/releases/tag/tycho-2.6.0), I haven't checked the changelog though._
> 
> It can't be `p2-maven-plugin` anyway as it is only used to generate a p2 repository (that is used in the `.target` files), and it is only used in `releng/third-party`.

I played around with it further. tycho uses JDT under the covers. And it seems to be an issue between Tycho JDT and JDK17. mvn -X shows nice parameters were passed to JDT but I didn't look into it. I will try to see what happens when switching the tycho compiler to javac. Don't know whether that's possible/a good idea...

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PR: https://git.openjdk.java.net/jmc/pull/363